The invention relates to plasma display, driving apparatus for a plasma display panel and driving method thereof for use, for example, as a display apparatus for a personal computer or workstation, a flat type wall hanging television receiver, or for a display apparatus for advertising and information. This invention is preferably applicable to AC type plasma display devices.
In plasma display, one field is divided into several sub-fields, and each pixel (cell) emits light by exciting a phosphor using ultraviolet rays that are generated by a electric discharge carried out in the cell. The cell that emits light is selected by an address electric discharge between two set of electrodes which are provided perpendicular to each other on a front side glass substrate and a back side glass substrate, respectively, and are capable of being driven independently.
A first example of a plasma display device is disclosed, for example, in Japanese Patent Application Laid-Open No. 1994/186927. In this first example, the condition of electrically charged particles in all cells is equalized for surely prohibiting the lighting of some cells which are not intended to emit light, and two sets of light emitting discharges, that is, a full writing electric discharge and a full erasing electric discharge in each sub-field are carried out so as to be able to use a low voltage for an address electric discharge. Therefore, the contrast is deteriorated because light emitting occurs on the full panel when black is displayed.
A second example is disclosed, for example, in Japanese Patent Application Laid-Open No. 1995/49663. In the second example, a plurality of sub-fields having the same brightness gradations are arranged to form a sub-field block, and several blocks are provided. In sub-field blocks, a preliminary discharge, including a full writing electric discharge and a fine line erasing electric discharge, is performed in one sub-field, and a writing electric discharge and a erasing electric discharge for a pixel is carried out one time. Therefore, deterioration of the panel is reduced and the contrast of the display is improved. The second example discloses one solution to improve the contrast, but no means is disclosed to improve the contrast in an arrangement in which plural sub-fields having different brightness gradations are provided for forming one sub-field block.
About 3 xcexcsec to 4 xcexcsec is needed to write one line of plasma panel, and an ordinary television display has 480 lines. The writing period of a screen is 1.44 msec, if the writing period of one line is 3 sec, so that 1.44 msecxc3x979≈=13 msec is needed for one field. However, the period of one field is 16.7 msec. The sustaining period is 16.7 msec minus a writing period and preliminary discharge period, and so this period is not long enough. Further, if a display has 760 lines per screen, like a high definition display, or if a display has 8 sub-fields for providing 256 gradations, the period for writing will not be sufficient.
It is an object of the present invention to improve contrast in a display.
It is another object of the present invention to improve contrast in a display by reducing a full erasing electric discharge and full writing electric discharge.
It is still another object of the invention to improve contrast in a display by reducing a preliminary discharge without changing the number of sub-fields.
According to a feature of the present invention, to achieve the above objects, a plasma display and a plasma display driving system include a first electrode group, which is arranged on a permeable substrate and in which the electrodes are capable of being driven in common, a second electrode group, which is arranged in parallel with the first electrode group on the permeable substrate and in which the electrodes are capable of being driven independently, a third electrode group, which is arranged perpendicular to the first and second electrode groups on the other substrate and in which the electrodes are capable of being driven independently, and a plasma panel, and wherein the driving system comprises means for performing at least one electric discharge for equalizing electrically charged particles in a cell in which another electrically charged particle is produced beforehand.
According to another feature of the present invention, to achieve the above objects, a plasma display, and a plasma display panel driving system and circuit include a first electrode group in which the electrodes are driven in common, a second electrode group in which the electrodes are driven independently, a third electrode group for producing an address electric discharge, means for erasing and polarizing electrically charged particles by a fine line erasing pulse after a sustaining period and for supplying an equalizing pulse to one electrode of the one of the first and second electrode groups to which the last fine line erasing pulse was supplied and for supplying a regulating pulse to an electrode of the other of the first and the second electrode groups after the equalizing pulse has been supplied, thereby controlling the electrically charged particles without fully erasing the electric discharge and fully writing an electric discharge, while improving the contrast without a light emitting discharge in the case of a black display.
According to still another feature of the present invention, to achieve the above objects, a plasma display and a plasma display panel driving system and circuit include means for forming a field block from a plurality of sub-fields and for performing a full writing electric discharge and a fine line erasing electric discharge in a first sub-field of the field block for decreasing the number of electric discharges, means for gathering positive electrically charged particles in the vicinity of an address electrode by the full writing electric discharge and fine line erasing electric discharge, thereby decreasing the voltage level of an address pulse, and means for reproducing the condition of electrically charged particles to the same condition as after performing full writing electric discharge and fine line erasing electric discharge are performed by utilizing a sustaining electric discharge in a cell in which the address electric discharge occurred, thereby reducing the voltage of a address electric discharge in the next field, without the full writing electric discharge and the fine line electric discharge. In a cell having no address electric discharge, the condition of electrically charged particles after the full writing electric discharge and fine line erasing electric discharge are performed is maintained during one field, so that it is sufficient to perform full writing electric discharge and fine line electric discharge only one time.